/*
 * jpeglib.h
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1991-1998, Thomas G. Lane.
 * Modified 2002-2009 by Guido Vollbeding.
 * Modifications:
 * Copyright (C) 2009-2011, 2013, D. R. Commander.
 * mozjpeg Modifications:
 * Copyright (C) 2014, Mozilla Corporation.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file defines the application interface for the JPEG library.
 * Most applications using the library need only include this file,
 * and perhaps jerror.h if they want to know the exact error codes.
 */

#ifndef JPEGLIB_H
#define JPEGLIB_H

/*
 * First we include the configuration files that record how this
 * installation of the JPEG library is set up.  jconfig.h can be
 * generated automatically for many systems.  jmorecfg.h contains
 * manual configuration options that most people need not worry about.
 */

#ifndef JCONFIG_INCLUDED	/* in case jinclude.h already did */
#include "jconfig.h"		/* widely used configuration options */
#endif
#include "jmorecfg.h"		/* seldom changed options */


#ifdef __cplusplus
#ifndef DONT_USE_EXTERN_C
extern "C"
{
#endif
#endif


   /* Various constants determining the sizes of things.
    * All of these are specified by the JPEG standard, so don't change them
    * if you want to be compatible.
    */

#define DCTSIZE		    8	/* The basic DCT block is 8x8 samples */
#define DCTSIZE2	    64	/* DCTSIZE squared; # of elements in a block */
#define NUM_QUANT_TBLS      4	/* Quantization tables are numbered 0..3 */
#define NUM_HUFF_TBLS       4	/* Huffman tables are numbered 0..3 */
#define NUM_ARITH_TBLS      16	/* Arith-coding tables are numbered 0..15 */
#define MAX_COMPS_IN_SCAN   4	/* JPEG limit on # of components in one scan */
#define MAX_SAMP_FACTOR     4	/* JPEG limit on sampling factors */
   /* Unfortunately, some bozo at Adobe saw no reason to be bound by the standard;
    * the PostScript DCT filter can emit files with many more than 10 blocks/MCU.
    * If you happen to run across such a file, you can up D_MAX_BLOCKS_IN_MCU
    * to handle it.  We even let you do this from the jconfig.h file.  However,
    * we strongly discourage changing C_MAX_BLOCKS_IN_MCU; just because Adobe
    * sometimes emits noncompliant files doesn't mean you should too.
    */
#define C_MAX_BLOCKS_IN_MCU   10 /* compressor's limit on blocks per MCU */
#ifndef D_MAX_BLOCKS_IN_MCU
#define D_MAX_BLOCKS_IN_MCU   10 /* decompressor's limit on blocks per MCU */
#endif


   /* Data structures for images (arrays of samples and of DCT coefficients).
    * On 80x86 machines, the image arrays are too big for near pointers,
    * but the pointer arrays can fit in near memory.
    */

   typedef JSAMPLE FAR *JSAMPROW; /* ptr to one image row of pixel samples. */
   typedef JSAMPROW *JSAMPARRAY; /* ptr to some rows (a 2-D sample array) */
   typedef JSAMPARRAY *JSAMPIMAGE; /* a 3-D sample array: top index is color */

   typedef JCOEF JBLOCK[DCTSIZE2]; /* one block of coefficients */
   typedef JBLOCK FAR *JBLOCKROW; /* pointer to one row of coefficient blocks */
   typedef JBLOCKROW *JBLOCKARRAY; /* a 2-D array of coefficient blocks */
   typedef JBLOCKARRAY *JBLOCKIMAGE; /* a 3-D array of coefficient blocks */

   typedef JCOEF FAR *JCOEFPTR; /* useful in a couple of places */


   /* Types for JPEG compression parameters and working tables. */

   /* DCT coefficient quantization tables. */

   typedef struct
   {
      /* This array gives the coefficient quantizers in natural array order
       * (not the zigzag order in which they are stored in a JPEG DQT marker).
       * CAUTION: IJG versions prior to v6a kept this array in zigzag order.
       */
      UINT16 quantval[DCTSIZE2]; /* quantization step for each coefficient */
      /* This field is used only during compression.  It's initialized FALSE when
       * the table is created, and set TRUE when it's been output to the file.
       * You could suppress output of a table by setting this to TRUE.
       * (See jpeg_suppress_tables for an example.)
       */
      boolean sent_table; /* TRUE when table has been output */
   } JQUANT_TBL;

   /* Huffman coding tables. */

   typedef struct
   {
      /* These two fields directly represent the contents of a JPEG DHT marker */
      UINT8 bits[17]; /* bits[k] = # of symbols with codes of */
      /* length k bits; bits[0] is unused */
      UINT8 huffval[256]; /* The symbols, in order of incr code length */
      /* This field is used only during compression.  It's initialized FALSE when
       * the table is created, and set TRUE when it's been output to the file.
       * You could suppress output of a table by setting this to TRUE.
       * (See jpeg_suppress_tables for an example.)
       */
      boolean sent_table; /* TRUE when table has been output */
   } JHUFF_TBL;

   /* Basic info about one component (color channel). */

   typedef struct
   {
      /* These values are fixed over the whole image. */
      /* For compression, they must be supplied by parameter setup; */
      /* for decompression, they are read from the SOF marker. */
      int component_id; /* identifier for this component (0..255) */
      int component_index; /* its index in SOF or cinfo->comp_info[] */
      int h_samp_factor; /* horizontal sampling factor (1..4) */
      int v_samp_factor; /* vertical sampling factor (1..4) */
      int quant_tbl_no; /* quantization table selector (0..3) */
      /* These values may vary between scans. */
      /* For compression, they must be supplied by parameter setup; */
      /* for decompression, they are read from the SOS marker. */
      /* The decompressor output side may not use these variables. */
      int dc_tbl_no; /* DC entropy table selector (0..3) */
      int ac_tbl_no; /* AC entropy table selector (0..3) */

      /* Remaining fields should be treated as private by applications. */

      /* These values are computed during compression or decompression startup: */
      /* Component's size in DCT blocks.
       * Any dummy blocks added to complete an MCU are not counted; therefore
       * these values do not depend on whether a scan is interleaved or not.
       */
      JDIMENSION width_in_blocks;
      JDIMENSION height_in_blocks;
      /* Size of a DCT block in samples.  Always DCTSIZE for compression.
       * For decompression this is the size of the output from one DCT block,
       * reflecting any scaling we choose to apply during the IDCT step.
       * Values of 1,2,4,8 are likely to be supported.  Note that different
       * components may receive different IDCT scalings.
       */
#if JPEG_LIB_VERSION >= 70
      int DCT_h_scaled_size;
      int DCT_v_scaled_size;
#else
      int DCT_scaled_size;
#endif
      /* The downsampled dimensions are the component's actual, unpadded number
       * of samples at the main buffer (preprocessing/compression interface), thus
       * downsampled_width = ceil(image_width * Hi/Hmax)
       * and similarly for height.  For decompression, IDCT scaling is included, so
       * downsampled_width = ceil(image_width * Hi/Hmax * DCT_[h_]scaled_size/DCTSIZE)
       */
      JDIMENSION downsampled_width; /* actual width in samples */
      JDIMENSION downsampled_height; /* actual height in samples */
      /* This flag is used only for decompression.  In cases where some of the
       * components will be ignored (eg grayscale output from YCbCr image),
       * we can skip most computations for the unused components.
       */
      boolean component_needed; /* do we need the value of this component? */

      /* These values are computed before starting a scan of the component. */
      /* The decompressor output side may not use these variables. */
      int MCU_width; /* number of blocks per MCU, horizontally */
      int MCU_height; /* number of blocks per MCU, vertically */
      int MCU_blocks; /* MCU_width * MCU_height */
      int MCU_sample_width; /* MCU width in samples, MCU_width*DCT_[h_]scaled_size */
      int last_col_width; /* # of non-dummy blocks across in last MCU */
      int last_row_height; /* # of non-dummy blocks down in last MCU */

      /* Saved quantization table for component; NULL if none yet saved.
       * See jdinput.c comments about the need for this information.
       * This field is currently used only for decompression.
       */
      JQUANT_TBL * quant_table;

      /* Private per-component storage for DCT or IDCT subsystem. */
      void * dct_table;
   } jpeg_component_info;

   /* The script for encoding a multiple-scan file is an array of these: */

   typedef struct
   {
      int comps_in_scan; /* number of components encoded in this scan */
      int component_index[MAX_COMPS_IN_SCAN]; /* their SOF/comp_info[] indexes */
      int Ss, Se; /* progressive JPEG spectral selection parms */
      int Ah, Al; /* progressive JPEG successive approx. parms */
   } jpeg_scan_info;

   /* The decompressor can save APPn and COM markers in a list of these: */

   typedef struct jpeg_marker_struct FAR * jpeg_saved_marker_ptr;

   struct jpeg_marker_struct
   {
      jpeg_saved_marker_ptr next; /* next in list, or NULL */
      UINT8 marker; /* marker code: JPEG_COM, or JPEG_APP0+n */
      unsigned int original_length; /* # bytes of data in the file */
      unsigned int data_length; /* # bytes of data saved at data[] */
      JOCTET FAR * data; /* the data contained in the marker */
      /* the marker length word is not counted in data_length or original_length */
   };

   /* Known color spaces. */

#define JCS_EXTENSIONS 1
#define JCS_ALPHA_EXTENSIONS 1

   typedef enum
   {
      JCS_UNKNOWN, /* error/unspecified */
      JCS_GRAYSCALE, /* monochrome */
      JCS_RGB, /* red/green/blue as specified by the RGB_RED, RGB_GREEN,
				   RGB_BLUE, and RGB_PIXELSIZE macros */
      JCS_YCbCr, /* Y/Cb/Cr (also known as YUV) */
      JCS_CMYK, /* C/M/Y/K */
      JCS_YCCK, /* Y/Cb/Cr/K */
      JCS_EXT_RGB, /* red/green/blue */
      JCS_EXT_RGBX, /* red/green/blue/x */
      JCS_EXT_BGR, /* blue/green/red */
      JCS_EXT_BGRX, /* blue/green/red/x */
      JCS_EXT_XBGR, /* x/blue/green/red */
      JCS_EXT_XRGB, /* x/red/green/blue */
      /* When out_color_space it set to JCS_EXT_RGBX, JCS_EXT_BGRX,
         JCS_EXT_XBGR, or JCS_EXT_XRGB during decompression, the X byte is
         undefined, and in order to ensure the best performance,
         libjpeg-turbo can set that byte to whatever value it wishes.  Use
         the following colorspace constants to ensure that the X byte is set
         to 0xFF, so that it can be interpreted as an opaque alpha
         channel. */
      JCS_EXT_RGBA, /* red/green/blue/alpha */
      JCS_EXT_BGRA, /* blue/green/red/alpha */
      JCS_EXT_ABGR, /* alpha/blue/green/red */
      JCS_EXT_ARGB /* alpha/red/green/blue */
   } J_COLOR_SPACE;

   /* DCT/IDCT algorithm options. */

   typedef enum
   {
      JDCT_ISLOW, /* slow but accurate integer algorithm */
      JDCT_IFAST, /* faster, less accurate integer method */
      JDCT_FLOAT /* floating-point: accurate, fast on fast HW */
   } J_DCT_METHOD;

#ifndef JDCT_DEFAULT		/* may be overridden in jconfig.h */
#define JDCT_DEFAULT  JDCT_ISLOW
#endif
#ifndef JDCT_FASTEST		/* may be overridden in jconfig.h */
#define JDCT_FASTEST  JDCT_IFAST
#endif

   /* Dithering options for decompression. */

   typedef enum
   {
      JDITHER_NONE, /* no dithering */
      JDITHER_ORDERED, /* simple ordered dither */
      JDITHER_FS /* Floyd-Steinberg error diffusion dither */
   } J_DITHER_MODE;


   /* Common fields between JPEG compression and decompression master structs. */

#define jpeg_common_fields \
  struct jpeg_error_mgr* err;	/* Error handler module */\
  struct jpeg_memory_mgr* mem;	/* Memory manager module */\
  struct jpeg_progress_mgr* progress; /* Progress monitor, or NULL if none */\
  void* client_data;		/* Available for use by application */\
  boolean is_decompressor;	/* So common code can tell which is which */\
  int global_state		/* For checking call sequence validity */

   /* Routines that are to be used by both halves of the library are declared
    * to receive a pointer to this structure.  There are no actual instances of
    * jpeg_common_struct, only of jpeg_compress_struct and jpeg_decompress_struct.
    */
   struct jpeg_common_struct
   {
      jpeg_common_fields; /* Fields common to both master struct types */
      /* Additional fields follow in an actual jpeg_compress_struct or
       * jpeg_decompress_struct.  All three structs must agree on these
       * initial fields!  (This would be a lot cleaner in C++.)
       */
   };

   typedef struct jpeg_common_struct* j_common_ptr;
   typedef struct jpeg_compress_struct* j_compress_ptr;
   typedef struct jpeg_decompress_struct* j_decompress_ptr;

   /* Master record for a compression instance */

   struct jpeg_compress_struct
   {
      jpeg_common_fields; /* Fields shared with jpeg_decompress_struct */

      /* Destination for compressed data */
      struct jpeg_destination_mgr * dest;

      /* Description of source image --- these fields must be filled in by
       * outer application before starting compression.  in_color_space must
       * be correct before you can even call jpeg_set_defaults().
       */

      JDIMENSION image_width; /* input image width */
      JDIMENSION image_height; /* input image height */
      int input_components; /* # of color components in input image */
      J_COLOR_SPACE in_color_space; /* colorspace of input image */

      double input_gamma; /* image gamma of input image */

      /* Compression parameters --- these fields must be set before calling
       * jpeg_start_compress().  We recommend calling jpeg_set_defaults() to
       * initialize everything to reasonable defaults, then changing anything
       * the application specifically wants to change.  That way you won't get
       * burnt when new parameters are added.  Also note that there are several
       * helper routines to simplify changing parameters.
       */

#if JPEG_LIB_VERSION >= 70
      unsigned int scale_num, scale_denom; /* fraction by which to scale image */

      JDIMENSION jpeg_width; /* scaled JPEG image width */
      JDIMENSION jpeg_height; /* scaled JPEG image height */
      /* Dimensions of actual JPEG image that will be written to file,
       * derived from input dimensions by scaling factors above.
       * These fields are computed by jpeg_start_compress().
       * You can also use jpeg_calc_jpeg_dimensions() to determine these values
       * in advance of calling jpeg_start_compress().
       */
#endif

      int data_precision; /* bits of precision in image data */

      int num_components; /* # of color components in JPEG image */
      J_COLOR_SPACE jpeg_color_space; /* colorspace of JPEG image */

      jpeg_component_info* comp_info;
      /* comp_info[i] describes component that appears i'th in SOF */

      JQUANT_TBL* quant_tbl_ptrs[NUM_QUANT_TBLS];
#if JPEG_LIB_VERSION >= 70
      int q_scale_factor[NUM_QUANT_TBLS];
#endif
      /* ptrs to coefficient quantization tables, or NULL if not defined,
       * and corresponding scale factors (percentage, initialized 100).
       */

      JHUFF_TBL* dc_huff_tbl_ptrs[NUM_HUFF_TBLS];
      JHUFF_TBL* ac_huff_tbl_ptrs[NUM_HUFF_TBLS];
      /* ptrs to Huffman coding tables, or NULL if not defined */

      UINT8 arith_dc_L[NUM_ARITH_TBLS]; /* L values for DC arith-coding tables */
      UINT8 arith_dc_U[NUM_ARITH_TBLS]; /* U values for DC arith-coding tables */
      UINT8 arith_ac_K[NUM_ARITH_TBLS]; /* Kx values for AC arith-coding tables */

      int num_scans; /* # of entries in scan_info array */
      const jpeg_scan_info* scan_info; /* script for multi-scan file, or NULL */
      /* The default value of scan_info is NULL, which causes a single-scan
       * sequential JPEG file to be emitted.  To create a multi-scan file,
       * set num_scans and scan_info to point to an array of scan definitions.
       */

      boolean raw_data_in; /* TRUE=caller supplies downsampled data */
      boolean arith_code; /* TRUE=arithmetic coding, FALSE=Huffman */
      boolean optimize_coding; /* TRUE=optimize entropy encoding parms */
      boolean CCIR601_sampling; /* TRUE=first samples are cosited */
#if JPEG_LIB_VERSION >= 70
      boolean do_fancy_downsampling; /* TRUE=apply fancy downsampling */
#endif
      int smoothing_factor; /* 1..100, or 0 for no input smoothing */
      J_DCT_METHOD dct_method; /* DCT algorithm selector */

      boolean use_moz_defaults; /* TRUE=use Mozilla defaults */
      boolean optimize_scans; /* TRUE=optimize progressive coding scans */
      boolean one_dc_scan; /* TRUE=use a single DC scan interleaving all components */
      boolean trellis_quant; /* TRUE=use trellis quantization */
      boolean trellis_eob_opt; /* TRUE=optimize for sequences of EOB */
      boolean use_flat_quant_tbl; /* TRUE=use flat quantization table */
      boolean use_lambda_weight_tbl; /* TRUE=use lambda weighting table */
      boolean use_scans_in_trellis; /* TRUE=use scans in trellis optimization */
      boolean trellis_passes; /* TRUE=currently doing trellis-related passes */
      boolean trellis_q_opt; /* TRUE=optimize quant table in trellis loop */

      double norm_src[NUM_QUANT_TBLS][DCTSIZE2];
      double norm_coef[NUM_QUANT_TBLS][DCTSIZE2];

      int trellis_freq_split; /* splitting point for frequency in trellis quantization */
      int trellis_num_loops; /* number of trellis loops */

      int num_scans_luma; /* # of entries in scan_info array pertaining to luma (used when optimize_scans is TRUE */
      int num_scans_luma_dc;
      int num_scans_chroma_dc;
      int num_frequency_splits;

      int Al_max_luma; /* maximum value of Al tested when optimizing scans (luma) */
      int Al_max_chroma; /* maximum value of Al tested when optimizing scans (chroma) */

      float lambda_log_scale1;
      float lambda_log_scale2;

      /* The restart interval can be specified in absolute MCUs by setting
       * restart_interval, or in MCU rows by setting restart_in_rows
       * (in which case the correct restart_interval will be figured
       * for each scan).
       */
      unsigned int restart_interval; /* MCUs per restart, or 0 for no restart */
      int restart_in_rows; /* if > 0, MCU rows per restart interval */

      /* Parameters controlling emission of special markers. */

      boolean write_JFIF_header; /* should a JFIF marker be written? */
      UINT8 JFIF_major_version; /* What to write for the JFIF version number */
      UINT8 JFIF_minor_version;
      /* These three values are not used by the JPEG code, merely copied */
      /* into the JFIF APP0 marker.  density_unit can be 0 for unknown, */
      /* 1 for dots/inch, or 2 for dots/cm.  Note that the pixel aspect */
      /* ratio is defined by X_density/Y_density even when density_unit=0. */
      UINT8 density_unit; /* JFIF code for pixel size units */
      UINT16 X_density; /* Horizontal pixel density */
      UINT16 Y_density; /* Vertical pixel density */
      boolean write_Adobe_marker; /* should an Adobe marker be written? */

      /* State variable: index of next scanline to be written to
       * jpeg_write_scanlines().  Application may use this to control its
       * processing loop, e.g., "while (next_scanline < image_height)".
       */

      JDIMENSION next_scanline; /* 0 .. image_height-1  */

      /* Remaining fields are known throughout compressor, but generally
       * should not be touched by a surrounding application.
       */

      /*
       * These fields are computed during compression startup
       */
      boolean progressive_mode; /* TRUE if scan script uses progressive mode */
      int max_h_samp_factor; /* largest h_samp_factor */
      int max_v_samp_factor; /* largest v_samp_factor */

#if JPEG_LIB_VERSION >= 70
      int min_DCT_h_scaled_size; /* smallest DCT_h_scaled_size of any component */
      int min_DCT_v_scaled_size; /* smallest DCT_v_scaled_size of any component */
#endif

      JDIMENSION total_iMCU_rows; /* # of iMCU rows to be input to coef ctlr */
      /* The coefficient controller receives data in units of MCU rows as defined
       * for fully interleaved scans (whether the JPEG file is interleaved or not).
       * There are v_samp_factor * DCTSIZE sample rows of each component in an
       * "iMCU" (interleaved MCU) row.
       */

      /*
       * These fields are valid during any one scan.
       * They describe the components and MCUs actually appearing in the scan.
       */
      int comps_in_scan; /* # of JPEG components in this scan */
      jpeg_component_info * cur_comp_info[MAX_COMPS_IN_SCAN];
      /* *cur_comp_info[i] describes component that appears i'th in SOS */

      JDIMENSION MCUs_per_row; /* # of MCUs across the image */
      JDIMENSION MCU_rows_in_scan; /* # of MCU rows in the image */

      int blocks_in_MCU; /* # of DCT blocks per MCU */
      int MCU_membership[C_MAX_BLOCKS_IN_MCU];
      /* MCU_membership[i] is index in cur_comp_info of component owning */
      /* i'th block in an MCU */

      int Ss, Se, Ah, Al; /* progressive JPEG parameters for scan */

#if JPEG_LIB_VERSION >= 80
      int block_size; /* the basic DCT block size: 1..16 */
      const int * natural_order; /* natural-order position array */
      int lim_Se; /* min( Se, DCTSIZE2-1 ) */
#endif

      /*
       * Links to compression subobjects (methods and private variables of modules)
       */
      struct jpeg_comp_master* master;
      struct jpeg_c_main_controller* main;
      struct jpeg_c_prep_controller* prep;
      struct jpeg_c_coef_controller* coef;
      struct jpeg_marker_writer* marker;
      struct jpeg_color_converter* cconvert;
      struct jpeg_downsampler* downsample;
      struct jpeg_forward_dct* fdct;
      struct jpeg_entropy_encoder* entropy;
      jpeg_scan_info* script_space; /* workspace for jpeg_simple_progression */
      int script_space_size;
   };

   /* Master record for a decompression instance */

   struct jpeg_decompress_struct
   {
      jpeg_common_fields; /* Fields shared with jpeg_compress_struct */

      /* Source of compressed data */
      struct jpeg_source_mgr * src;

      /* Basic description of image --- filled in by jpeg_read_header(). */
      /* Application may inspect these values to decide how to process image. */

      JDIMENSION image_width; /* nominal image width (from SOF marker) */
      JDIMENSION image_height; /* nominal image height */
      int num_components; /* # of color components in JPEG image */
      J_COLOR_SPACE jpeg_color_space; /* colorspace of JPEG image */

      /* Decompression processing parameters --- these fields must be set before
       * calling jpeg_start_decompress().  Note that jpeg_read_header() initializes
       * them to default values.
       */

      J_COLOR_SPACE out_color_space; /* colorspace for output */

      unsigned int scale_num, scale_denom; /* fraction by which to scale image */

      double output_gamma; /* image gamma wanted in output */

      boolean buffered_image; /* TRUE=multiple output passes */
      boolean raw_data_out; /* TRUE=downsampled data wanted */

      J_DCT_METHOD dct_method; /* IDCT algorithm selector */
      boolean do_fancy_upsampling; /* TRUE=apply fancy upsampling */
      boolean do_block_smoothing; /* TRUE=apply interblock smoothing */

      boolean quantize_colors; /* TRUE=colormapped output wanted */
      /* the following are ignored if not quantize_colors: */
      J_DITHER_MODE dither_mode; /* type of color dithering to use */
      boolean two_pass_quantize; /* TRUE=use two-pass color quantization */
      int desired_number_of_colors; /* max # colors to use in created colormap */
      /* these are significant only in buffered-image mode: */
      boolean enable_1pass_quant; /* enable future use of 1-pass quantizer */
      boolean enable_external_quant; /* enable future use of external colormap */
      boolean enable_2pass_quant; /* enable future use of 2-pass quantizer */

      /* Description of actual output image that will be returned to application.
       * These fields are computed by jpeg_start_decompress().
       * You can also use jpeg_calc_output_dimensions() to determine these values
       * in advance of calling jpeg_start_decompress().
       */

      JDIMENSION output_width; /* scaled image width */
      JDIMENSION output_height; /* scaled image height */
      int out_color_components; /* # of color components in out_color_space */
      int output_components; /* # of color components returned */
      /* output_components is 1 (a colormap index) when quantizing colors;
       * otherwise it equals out_color_components.
       */
      int rec_outbuf_height; /* min recommended height of scanline buffer */
      /* If the buffer passed to jpeg_read_scanlines() is less than this many rows
       * high, space and time will be wasted due to unnecessary data copying.
       * Usually rec_outbuf_height will be 1 or 2, at most 4.
       */

      /* When quantizing colors, the output colormap is described by these fields.
       * The application can supply a colormap by setting colormap non-NULL before
       * calling jpeg_start_decompress; otherwise a colormap is created during
       * jpeg_start_decompress or jpeg_start_output.
       * The map has out_color_components rows and actual_number_of_colors columns.
       */
      int actual_number_of_colors; /* number of entries in use */
      JSAMPARRAY colormap; /* The color map as a 2-D pixel array */

      /* State variables: these variables indicate the progress of decompression.
       * The application may examine these but must not modify them.
       */

      /* Row index of next scanline to be read from jpeg_read_scanlines().
       * Application may use this to control its processing loop, e.g.,
       * "while (output_scanline < output_height)".
       */
      JDIMENSION output_scanline; /* 0 .. output_height-1  */

      /* Current input scan number and number of iMCU rows completed in scan.
       * These indicate the progress of the decompressor input side.
       */
      int input_scan_number; /* Number of SOS markers seen so far */
      JDIMENSION input_iMCU_row; /* Number of iMCU rows completed */

      /* The "output scan number" is the notional scan being displayed by the
       * output side.  The decompressor will not allow output scan/row number
       * to get ahead of input scan/row, but it can fall arbitrarily far behind.
       */
      int output_scan_number; /* Nominal scan number being displayed */
      JDIMENSION output_iMCU_row; /* Number of iMCU rows read */

      /* Current progression status.  coef_bits[c][i] indicates the precision
       * with which component c's DCT coefficient i (in zigzag order) is known.
       * It is -1 when no data has yet been received, otherwise it is the point
       * transform (shift) value for the most recent scan of the coefficient
       * (thus, 0 at completion of the progression).
       * This pointer is NULL when reading a non-progressive file.
       */
      int (*coef_bits )[DCTSIZE2]; /* -1 or current Al value for each coef */

      /* Internal JPEG parameters --- the application usually need not look at
       * these fields.  Note that the decompressor output side may not use
       * any parameters that can change between scans.
       */

      /* Quantization and Huffman tables are carried forward across input
       * datastreams when processing abbreviated JPEG datastreams.
       */

      JQUANT_TBL * quant_tbl_ptrs[NUM_QUANT_TBLS];
      /* ptrs to coefficient quantization tables, or NULL if not defined */

      JHUFF_TBL * dc_huff_tbl_ptrs[NUM_HUFF_TBLS];
      JHUFF_TBL * ac_huff_tbl_ptrs[NUM_HUFF_TBLS];
      /* ptrs to Huffman coding tables, or NULL if not defined */

      /* These parameters are never carried across datastreams, since they
       * are given in SOF/SOS markers or defined to be reset by SOI.
       */

      int data_precision; /* bits of precision in image data */

      jpeg_component_info * comp_info;
      /* comp_info[i] describes component that appears i'th in SOF */

#if JPEG_LIB_VERSION >= 80
      boolean is_baseline; /* TRUE if Baseline SOF0 encountered */
#endif
      boolean progressive_mode; /* TRUE if SOFn specifies progressive mode */
      boolean arith_code; /* TRUE=arithmetic coding, FALSE=Huffman */

      UINT8 arith_dc_L[NUM_ARITH_TBLS]; /* L values for DC arith-coding tables */
      UINT8 arith_dc_U[NUM_ARITH_TBLS]; /* U values for DC arith-coding tables */
      UINT8 arith_ac_K[NUM_ARITH_TBLS]; /* Kx values for AC arith-coding tables */

      unsigned int restart_interval; /* MCUs per restart interval, or 0 for no restart */

      /* These fields record data obtained from optional markers recognized by
       * the JPEG library.
       */
      boolean saw_JFIF_marker; /* TRUE iff a JFIF APP0 marker was found */
      /* Data copied from JFIF marker; only valid if saw_JFIF_marker is TRUE: */
      UINT8 JFIF_major_version; /* JFIF version number */
      UINT8 JFIF_minor_version;
      UINT8 density_unit; /* JFIF code for pixel size units */
      UINT16 X_density; /* Horizontal pixel density */
      UINT16 Y_density; /* Vertical pixel density */
      boolean saw_Adobe_marker; /* TRUE iff an Adobe APP14 marker was found */
      UINT8 Adobe_transform; /* Color transform code from Adobe marker */

      boolean CCIR601_sampling; /* TRUE=first samples are cosited */

      /* Aside from the specific data retained from APPn markers known to the
       * library, the uninterpreted contents of any or all APPn and COM markers
       * can be saved in a list for examination by the application.
       */
      jpeg_saved_marker_ptr marker_list; /* Head of list of saved markers */

      /* Remaining fields are known throughout decompressor, but generally
       * should not be touched by a surrounding application.
       */

      /*
       * These fields are computed during decompression startup
       */
      int max_h_samp_factor; /* largest h_samp_factor */
      int max_v_samp_factor; /* largest v_samp_factor */

#if JPEG_LIB_VERSION >= 70
      int min_DCT_h_scaled_size; /* smallest DCT_h_scaled_size of any component */
      int min_DCT_v_scaled_size; /* smallest DCT_v_scaled_size of any component */
#else
      int min_DCT_scaled_size; /* smallest DCT_scaled_size of any component */
#endif

      JDIMENSION total_iMCU_rows; /* # of iMCU rows in image */
      /* The coefficient controller's input and output progress is measured in
       * units of "iMCU" (interleaved MCU) rows.  These are the same as MCU rows
       * in fully interleaved JPEG scans, but are used whether the scan is
       * interleaved or not.  We define an iMCU row as v_samp_factor DCT block
       * rows of each component.  Therefore, the IDCT output contains
       * v_samp_factor*DCT_[v_]scaled_size sample rows of a component per iMCU row.
       */

      JSAMPLE * sample_range_limit; /* table for fast range-limiting */

      /*
       * These fields are valid during any one scan.
       * They describe the components and MCUs actually appearing in the scan.
       * Note that the decompressor output side must not use these fields.
       */
      int comps_in_scan; /* # of JPEG components in this scan */
      jpeg_component_info * cur_comp_info[MAX_COMPS_IN_SCAN];
      /* *cur_comp_info[i] describes component that appears i'th in SOS */

      JDIMENSION MCUs_per_row; /* # of MCUs across the image */
      JDIMENSION MCU_rows_in_scan; /* # of MCU rows in the image */

      int blocks_in_MCU; /* # of DCT blocks per MCU */
      int MCU_membership[D_MAX_BLOCKS_IN_MCU];
      /* MCU_membership[i] is index in cur_comp_info of component owning */
      /* i'th block in an MCU */

      int Ss, Se, Ah, Al; /* progressive JPEG parameters for scan */

#if JPEG_LIB_VERSION >= 80
      /* These fields are derived from Se of first SOS marker.
       */
      int block_size; /* the basic DCT block size: 1..16 */
      const int * natural_order; /* natural-order position array for entropy decode */
      int lim_Se; /* min( Se, DCTSIZE2-1 ) for entropy decode */
#endif

      /* This field is shared between entropy decoder and marker parser.
       * It is either zero or the code of a JPEG marker that has been
       * read from the data source, but has not yet been processed.
       */
      int unread_marker;

      /*
       * Links to decompression subobjects (methods, private variables of modules)
       */
      struct jpeg_decomp_master * master;
      struct jpeg_d_main_controller * main;
      struct jpeg_d_coef_controller * coef;
      struct jpeg_d_post_controller * post;
      struct jpeg_input_controller * inputctl;
      struct jpeg_marker_reader * marker;
      struct jpeg_entropy_decoder * entropy;
      struct jpeg_inverse_dct * idct;
      struct jpeg_upsampler * upsample;
      struct jpeg_color_deconverter * cconvert;
      struct jpeg_color_quantizer * cquantize;
   };


   /* "Object" declarations for JPEG modules that may be supplied or called
    * directly by the surrounding application.
    * As with all objects in the JPEG library, these structs only define the
    * publicly visible methods and state variables of a module.  Additional
    * private fields may exist after the public ones.
    */

   /* Error handler object */

   struct jpeg_error_mgr
   {
      /* Error exit handler: does not return to caller */
      JMETHOD( void, error_exit, ( j_common_ptr cinfo ) );
      /* Conditionally emit a trace or warning message */
      JMETHOD( void, emit_message, ( j_common_ptr cinfo, int msg_level) );
      /* Routine that actually outputs a trace or error message */
      JMETHOD( void, output_message, ( j_common_ptr cinfo ) );
      /* Format a message string for the most recent JPEG error or message */
      JMETHOD( void, format_message, ( j_common_ptr cinfo, char * buffer ) );
#define JMSG_LENGTH_MAX  200	/* recommended size of format_message buffer */
      /* Reset error state variables at start of a new image */
      JMETHOD( void, reset_error_mgr, ( j_common_ptr cinfo ) );

      /* The message ID code and any parameters are saved here.
       * A message can have one string parameter or up to 8 int parameters.
       */
      int msg_code;
#define JMSG_STR_PARM_MAX  80

      union
      {
         int i[8];
         char s[JMSG_STR_PARM_MAX];
      } msg_parm;

      /* Standard state variables for error facility */

      int trace_level; /* max msg_level that will be displayed */

      /* For recoverable corrupt-data errors, we emit a warning message,
       * but keep going unless emit_message chooses to abort.  emit_message
       * should count warnings in num_warnings.  The surrounding application
       * can check for bad data by seeing if num_warnings is nonzero at the
       * end of processing.
       */
      long num_warnings; /* number of corrupt-data warnings */

      /* These fields point to the table(s) of error message strings.
       * An application can change the table pointer to switch to a different
       * message list (typically, to change the language in which errors are
       * reported).  Some applications may wish to add additional error codes
       * that will be handled by the JPEG library error mechanism; the second
       * table pointer is used for this purpose.
       *
       * First table includes all errors generated by JPEG library itself.
       * Error code 0 is reserved for a "no such error string" message.
       */
      const char * const * jpeg_message_table; /* Library errors */
      int last_jpeg_message; /* Table contains strings 0..last_jpeg_message */
      /* Second table can be added by application (see cjpeg/djpeg for example).
       * It contains strings numbered first_addon_message..last_addon_message.
       */
      const char * const * addon_message_table; /* Non-library errors */
      int first_addon_message; /* code for first string in addon table */
      int last_addon_message; /* code for last string in addon table */
   };

   /* Progress monitor object */

   struct jpeg_progress_mgr
   {
      JMETHOD( void, progress_monitor, ( j_common_ptr cinfo ) );

      long pass_counter; /* work units completed in this pass */
      long pass_limit; /* total number of work units in this pass */
      int completed_passes; /* passes completed so far */
      int total_passes; /* total number of passes expected */
   };

   /* Data destination object for compression */

   struct jpeg_destination_mgr
   {
      JOCTET * next_output_byte; /* => next byte to write in buffer */
      size_t free_in_buffer; /* # of byte spaces remaining in buffer */

      JMETHOD( void, init_destination, ( j_compress_ptr cinfo ) );
      JMETHOD( boolean, empty_output_buffer, ( j_compress_ptr cinfo ) );
      JMETHOD( void, term_destination, ( j_compress_ptr cinfo ) );
   };

   /* Data source object for decompression */

   struct jpeg_source_mgr
   {
      const JOCTET * next_input_byte; /* => next byte to read from buffer */
      size_t bytes_in_buffer; /* # of bytes remaining in buffer */

      JMETHOD( void, init_source, ( j_decompress_ptr cinfo ) );
      JMETHOD( boolean, fill_input_buffer, ( j_decompress_ptr cinfo ) );
      JMETHOD( void, skip_input_data, ( j_decompress_ptr cinfo, long num_bytes) );
      JMETHOD( boolean, resync_to_restart, ( j_decompress_ptr cinfo, int desired) );
      JMETHOD( void, term_source, ( j_decompress_ptr cinfo ) );
   };


   /* Memory manager object.
    * Allocates "small" objects (a few K total), "large" objects (tens of K),
    * and "really big" objects (virtual arrays with backing store if needed).
    * The memory manager does not allow individual objects to be freed; rather,
    * each created object is assigned to a pool, and whole pools can be freed
    * at once.  This is faster and more convenient than remembering exactly what
    * to free, especially where malloc()/free() are not too speedy.
    * NB: alloc routines never return NULL.  They exit to error_exit if not
    * successful.
    */

#define JPOOL_PERMANENT	0	/* lasts until master record is destroyed */
#define JPOOL_IMAGE	1	/* lasts until done with image/datastream */
#define JPOOL_NUMPOOLS	2

   typedef struct jvirt_sarray_control * jvirt_sarray_ptr;
   typedef struct jvirt_barray_control * jvirt_barray_ptr;

   struct jpeg_memory_mgr
   {
      /* Method pointers */
      JMETHOD( void *, alloc_small, ( j_common_ptr cinfo, int pool_id,
         size_t sizeofobject ) );
      JMETHOD( void FAR *, alloc_large, ( j_common_ptr cinfo, int pool_id,
         size_t sizeofobject ) );
      JMETHOD( JSAMPARRAY, alloc_sarray, ( j_common_ptr cinfo, int pool_id,
         JDIMENSION samplesperrow,
         JDIMENSION numrows ) );
      JMETHOD( JBLOCKARRAY, alloc_barray, ( j_common_ptr cinfo, int pool_id,
         JDIMENSION blocksperrow,
         JDIMENSION numrows ) );
      JMETHOD( jvirt_sarray_ptr, request_virt_sarray, ( j_common_ptr cinfo,
         int pool_id,
         boolean pre_zero,
         JDIMENSION samplesperrow,
         JDIMENSION numrows,
         JDIMENSION maxaccess ) );
      JMETHOD( jvirt_barray_ptr, request_virt_barray, ( j_common_ptr cinfo,
         int pool_id,
         boolean pre_zero,
         JDIMENSION blocksperrow,
         JDIMENSION numrows,
         JDIMENSION maxaccess ) );
      JMETHOD( void, realize_virt_arrays, ( j_common_ptr cinfo ) );
      JMETHOD( JSAMPARRAY, access_virt_sarray, ( j_common_ptr cinfo,
         jvirt_sarray_ptr ptr,
         JDIMENSION start_row,
         JDIMENSION num_rows,
         boolean writable ) );
      JMETHOD( JBLOCKARRAY, access_virt_barray, ( j_common_ptr cinfo,
         jvirt_barray_ptr ptr,
         JDIMENSION start_row,
         JDIMENSION num_rows,
         boolean writable ) );
      JMETHOD( void, free_pool, ( j_common_ptr cinfo, int pool_id) );
      JMETHOD( void, self_destruct, ( j_common_ptr cinfo ) );

      /* Limit on memory allocation for this JPEG object.  (Note that this is
       * merely advisory, not a guaranteed maximum; it only affects the space
       * used for virtual-array buffers.)  May be changed by outer application
       * after creating the JPEG object.
       */
      long max_memory_to_use;

      /* Maximum allocation request accepted by alloc_large. */
      long max_alloc_chunk;
   };


   /* Routine signature for application-supplied marker processing methods.
    * Need not pass marker code since it is stored in cinfo->unread_marker.
    */
   typedef JMETHOD( boolean, jpeg_marker_parser_method, ( j_decompress_ptr cinfo ) );


   /* Declarations for routines called by application.
    * The JPP macro hides prototype parameters from compilers that can't cope.
    * Note JPP requires double parentheses.
    */

#ifdef HAVE_PROTOTYPES
#define JPP(arglist)	arglist
#else
#define JPP(arglist)	()
#endif


   /* Short forms of external names for systems with brain-damaged linkers.
    * We shorten external names to be unique in the first six letters, which
    * is good enough for all known systems.
    * (If your compiler itself needs names to be unique in less than 15 
    * characters, you are out of luck.  Get a better compiler.)
    */

#ifdef NEED_SHORT_EXTERNAL_NAMES
#define jpeg_std_error		jStdError
#define jpeg_CreateCompress	jCreaCompress
#define jpeg_CreateDecompress	jCreaDecompress
#define jpeg_destroy_compress	jDestCompress
#define jpeg_destroy_decompress	jDestDecompress
#define jpeg_stdio_dest		jStdDest
#define jpeg_stdio_src		jStdSrc
#if JPEG_LIB_VERSION >= 80 || defined(MEM_SRCDST_SUPPORTED)
#define jpeg_mem_dest		jMemDest
#define jpeg_mem_src		jMemSrc
#endif
#define jpeg_set_defaults	jSetDefaults
#define jpeg_set_colorspace	jSetColorspace
#define jpeg_default_colorspace	jDefColorspace
#define jpeg_set_quality	jSetQuality
#define jpeg_set_linear_quality	jSetLQuality
#if JPEG_LIB_VERSION >= 70
#define jpeg_default_qtables	jDefQTables
#endif
#define jpeg_add_quant_table	jAddQuantTable
#define jpeg_quality_scaling	jQualityScaling
#define jpeg_simple_progression	jSimProgress
#define jpeg_suppress_tables	jSuppressTables
#define jpeg_alloc_quant_table	jAlcQTable
#define jpeg_alloc_huff_table	jAlcHTable
#define jpeg_start_compress	jStrtCompress
#define jpeg_write_scanlines	jWrtScanlines
#define jpeg_finish_compress	jFinCompress
#if JPEG_LIB_VERSION >= 70
#define jpeg_calc_jpeg_dimensions	jCjpegDimensions
#endif
#define jpeg_write_raw_data	jWrtRawData
#define jpeg_write_marker	jWrtMarker
#define jpeg_write_m_header	jWrtMHeader
#define jpeg_write_m_byte	jWrtMByte
#define jpeg_write_tables	jWrtTables
#define jpeg_read_header	jReadHeader
#define jpeg_start_decompress	jStrtDecompress
#define jpeg_read_scanlines	jReadScanlines
#define jpeg_finish_decompress	jFinDecompress
#define jpeg_read_raw_data	jReadRawData
#define jpeg_has_multiple_scans	jHasMultScn
#define jpeg_start_output	jStrtOutput
#define jpeg_finish_output	jFinOutput
#define jpeg_input_complete	jInComplete
#define jpeg_new_colormap	jNewCMap
#define jpeg_consume_input	jConsumeInput
#if JPEG_LIB_VERSION >= 80
#define jpeg_core_output_dimensions	jCoreDimensions
#endif
#define jpeg_calc_output_dimensions	jCalcDimensions
#define jpeg_save_markers	jSaveMarkers
#define jpeg_set_marker_processor	jSetMarker
#define jpeg_read_coefficients	jReadCoefs
#define jpeg_write_coefficients	jWrtCoefs
#define jpeg_copy_critical_parameters	jCopyCrit
#define jpeg_abort_compress	jAbrtCompress
#define jpeg_abort_decompress	jAbrtDecompress
#define jpeg_abort		jAbort
#define jpeg_destroy		jDestroy
#define jpeg_resync_to_restart	jResyncRestart
#endif /* NEED_SHORT_EXTERNAL_NAMES */


   /* Default error-management setup */
   EXTERN( struct jpeg_error_mgr * ) jpeg_std_error
   JPP( (struct jpeg_error_mgr * err ) );

   /* Initialization of JPEG compression objects.
    * jpeg_create_compress() and jpeg_create_decompress() are the exported
    * names that applications should call.  These expand to calls on
    * jpeg_CreateCompress and jpeg_CreateDecompress with additional information
    * passed for version mismatch checking.
    * NB: you must set up the error-manager BEFORE calling jpeg_create_xxx.
    */
#define jpeg_create_compress(cinfo) \
    jpeg_CreateCompress((cinfo), JPEG_LIB_VERSION, \
			(size_t) sizeof(struct jpeg_compress_struct))
#define jpeg_create_decompress(cinfo) \
    jpeg_CreateDecompress((cinfo), JPEG_LIB_VERSION, \
			  (size_t) sizeof(struct jpeg_decompress_struct))
   EXTERN( void ) jpeg_CreateCompress JPP( ( j_compress_ptr cinfo,
      int version, size_t structsize ) );
   EXTERN( void ) jpeg_CreateDecompress JPP( ( j_decompress_ptr cinfo,
      int version, size_t structsize ) );
   /* Destruction of JPEG compression objects */
   EXTERN( void ) jpeg_destroy_compress JPP( ( j_compress_ptr cinfo ) );
   EXTERN( void ) jpeg_destroy_decompress JPP( ( j_decompress_ptr cinfo ) );

   /* Standard data source and destination managers: stdio streams. */
   /* Caller is responsible for opening the file before and closing after. */
   EXTERN( void ) jpeg_stdio_dest JPP( ( j_compress_ptr cinfo, FILE * outfile ) );
   EXTERN( void ) jpeg_stdio_src JPP( ( j_decompress_ptr cinfo, FILE * infile ) );

#if JPEG_LIB_VERSION >= 80 || defined(MEM_SRCDST_SUPPORTED)
   /* Data source and destination managers: memory buffers. */
   EXTERN( void ) jpeg_mem_dest JPP( ( j_compress_ptr cinfo,
      unsigned char ** outbuffer,
      unsigned long * outsize ) );
   EXTERN( void ) jpeg_mem_src JPP( ( j_decompress_ptr cinfo,
      unsigned char * inbuffer,
      unsigned long insize) );
#endif

   /* Default parameter setup for compression */
   EXTERN( void ) jpeg_set_defaults JPP( ( j_compress_ptr cinfo ) );
   /* Compression parameter setup aids */
   EXTERN( void ) jpeg_set_colorspace JPP( ( j_compress_ptr cinfo,
      J_COLOR_SPACE colorspace ) );
   EXTERN( void ) jpeg_default_colorspace JPP( ( j_compress_ptr cinfo ) );
   EXTERN( void ) jpeg_set_quality JPP( ( j_compress_ptr cinfo, int quality,
      boolean force_baseline ) );
   EXTERN( void ) jpeg_set_linear_quality JPP( ( j_compress_ptr cinfo,
      int scale_factor,
      boolean force_baseline ) );
#if JPEG_LIB_VERSION >= 70
   EXTERN( void ) jpeg_default_qtables JPP( ( j_compress_ptr cinfo,
      boolean force_baseline ) );
#endif
   EXTERN( void ) jpeg_add_quant_table JPP( ( j_compress_ptr cinfo, int which_tbl,
      const unsigned int *basic_table,
      int scale_factor,
      boolean force_baseline ) );
   EXTERN( int ) jpeg_quality_scaling JPP( (int quality) );
   EXTERN( void ) jpeg_simple_progression JPP( ( j_compress_ptr cinfo ) );
   EXTERN( void ) jpeg_suppress_tables JPP( ( j_compress_ptr cinfo,
      boolean suppress ) );
   EXTERN( JQUANT_TBL * ) jpeg_alloc_quant_table JPP( ( j_common_ptr cinfo ) );
   EXTERN( JHUFF_TBL * ) jpeg_alloc_huff_table JPP( ( j_common_ptr cinfo ) );

   /* Main entry points for compression */
   EXTERN( void ) jpeg_start_compress JPP( ( j_compress_ptr cinfo,
      boolean write_all_tables ) );
   EXTERN( JDIMENSION ) jpeg_write_scanlines JPP( ( j_compress_ptr cinfo,
      JSAMPARRAY scanlines,
      JDIMENSION num_lines ) );
   EXTERN( void ) jpeg_finish_compress JPP( ( j_compress_ptr cinfo ) );

#if JPEG_LIB_VERSION >= 70
   /* Precalculate JPEG dimensions for current compression parameters. */
   EXTERN( void ) jpeg_calc_jpeg_dimensions JPP( ( j_compress_ptr cinfo ) );
#endif

   /* Replaces jpeg_write_scanlines when writing raw downsampled data. */
   EXTERN( JDIMENSION ) jpeg_write_raw_data JPP( ( j_compress_ptr cinfo,
      JSAMPIMAGE data,
      JDIMENSION num_lines ) );

   /* Write a special marker.  See libjpeg.txt concerning safe usage. */
   EXTERN( void ) jpeg_write_marker
   JPP( ( j_compress_ptr cinfo, int marker,
      const JOCTET * dataptr, unsigned int datalen) );
   /* Same, but piecemeal. */
   EXTERN( void ) jpeg_write_m_header
   JPP( ( j_compress_ptr cinfo, int marker, unsigned int datalen) );
   EXTERN( void ) jpeg_write_m_byte
   JPP( ( j_compress_ptr cinfo, int val) );

   /* Alternate compression function: just write an abbreviated table file */
   EXTERN( void ) jpeg_write_tables JPP( ( j_compress_ptr cinfo ) );

   /* Decompression startup: read start of JPEG datastream to see what's there */
   EXTERN( int ) jpeg_read_header JPP( ( j_decompress_ptr cinfo,
      boolean require_image ) );
   /* Return value is one of: */
#define JPEG_SUSPENDED		0 /* Suspended due to lack of input data */
#define JPEG_HEADER_OK		1 /* Found valid image datastream */
#define JPEG_HEADER_TABLES_ONLY	2 /* Found valid table-specs-only datastream */
   /* If you pass require_image = TRUE (normal case), you need not check for
    * a TABLES_ONLY return code; an abbreviated file will cause an error exit.
    * JPEG_SUSPENDED is only possible if you use a data source module that can
    * give a suspension return (the stdio source module doesn't).
    */

   /* Main entry points for decompression */
   EXTERN( boolean ) jpeg_start_decompress JPP( ( j_decompress_ptr cinfo ) );
   EXTERN( JDIMENSION ) jpeg_read_scanlines JPP( ( j_decompress_ptr cinfo,
      JSAMPARRAY scanlines,
      JDIMENSION max_lines ) );
   EXTERN( boolean ) jpeg_finish_decompress JPP( ( j_decompress_ptr cinfo ) );

   /* Replaces jpeg_read_scanlines when reading raw downsampled data. */
   EXTERN( JDIMENSION ) jpeg_read_raw_data JPP( ( j_decompress_ptr cinfo,
      JSAMPIMAGE data,
      JDIMENSION max_lines ) );

   /* Additional entry points for buffered-image mode. */
   EXTERN( boolean ) jpeg_has_multiple_scans JPP( ( j_decompress_ptr cinfo ) );
   EXTERN( boolean ) jpeg_start_output JPP( ( j_decompress_ptr cinfo,
      int scan_number) );
   EXTERN( boolean ) jpeg_finish_output JPP( ( j_decompress_ptr cinfo ) );
   EXTERN( boolean ) jpeg_input_complete JPP( ( j_decompress_ptr cinfo ) );
   EXTERN( void ) jpeg_new_colormap JPP( ( j_decompress_ptr cinfo ) );
   EXTERN( int ) jpeg_consume_input JPP( ( j_decompress_ptr cinfo ) );
   /* Return value is one of: */
   /* #define JPEG_SUSPENDED	0    Suspended due to lack of input data */
#define JPEG_REACHED_SOS	1 /* Reached start of new scan */
#define JPEG_REACHED_EOI	2 /* Reached end of image */
#define JPEG_ROW_COMPLETED	3 /* Completed one iMCU row */
#define JPEG_SCAN_COMPLETED	4 /* Completed last iMCU row of a scan */

   /* Precalculate output dimensions for current decompression parameters. */
#if JPEG_LIB_VERSION >= 80
   EXTERN( void ) jpeg_core_output_dimensions JPP( ( j_decompress_ptr cinfo ) );
#endif
   EXTERN( void ) jpeg_calc_output_dimensions JPP( ( j_decompress_ptr cinfo ) );

   /* Control saving of COM and APPn markers into marker_list. */
   EXTERN( void ) jpeg_save_markers
   JPP( ( j_decompress_ptr cinfo, int marker_code,
      unsigned int length_limit) );

   /* Install a special processing method for COM or APPn markers. */
   EXTERN( void ) jpeg_set_marker_processor
   JPP( ( j_decompress_ptr cinfo, int marker_code,
      jpeg_marker_parser_method routine ) );

   /* Read or write raw DCT coefficients --- useful for lossless transcoding. */
   EXTERN( jvirt_barray_ptr * ) jpeg_read_coefficients JPP( ( j_decompress_ptr cinfo ) );
   EXTERN( void ) jpeg_write_coefficients JPP( ( j_compress_ptr cinfo,
      jvirt_barray_ptr * coef_arrays ) );
   EXTERN( void ) jpeg_copy_critical_parameters JPP( ( j_decompress_ptr srcinfo,
      j_compress_ptr dstinfo ) );

   /* If you choose to abort compression or decompression before completing
    * jpeg_finish_(de)compress, then you need to clean up to release memory,
    * temporary files, etc.  You can just call jpeg_destroy_(de)compress
    * if you're done with the JPEG object, but if you want to clean it up and
    * reuse it, call this:
    */
   EXTERN( void ) jpeg_abort_compress JPP( ( j_compress_ptr cinfo ) );
   EXTERN( void ) jpeg_abort_decompress JPP( ( j_decompress_ptr cinfo ) );

   /* Generic versions of jpeg_abort and jpeg_destroy that work on either
    * flavor of JPEG object.  These may be more convenient in some places.
    */
   EXTERN( void ) jpeg_abort JPP( ( j_common_ptr cinfo ) );
   EXTERN( void ) jpeg_destroy JPP( ( j_common_ptr cinfo ) );

   /* Default restart-marker-resync procedure for use by data source modules */
   EXTERN( boolean ) jpeg_resync_to_restart JPP( ( j_decompress_ptr cinfo,
      int desired) );


   /* These marker codes are exported since applications and data source modules
    * are likely to want to use them.
    */

#define JPEG_RST0	0xD0	/* RST0 marker code */
#define JPEG_EOI	0xD9	/* EOI marker code */
#define JPEG_APP0	0xE0	/* APP0 marker code */
#define JPEG_COM	0xFE	/* COM marker code */


   /* If we have a brain-damaged compiler that emits warnings (or worse, errors)
    * for structure definitions that are never filled in, keep it quiet by
    * supplying dummy definitions for the various substructures.
    */

#ifdef INCOMPLETE_TYPES_BROKEN
#ifndef JPEG_INTERNALS		/* will be defined in jpegint.h */

struct jvirt_sarray_control
   {
      long dummy;
   };

   struct jvirt_barray_control
   {
      long dummy;
   };

   struct jpeg_comp_master
   {
      long dummy;
   };

   struct jpeg_c_main_controller
   {
      long dummy;
   };

   struct jpeg_c_prep_controller
   {
      long dummy;
   };

   struct jpeg_c_coef_controller
   {
      long dummy;
   };

   struct jpeg_marker_writer
   {
      long dummy;
   };

   struct jpeg_color_converter
   {
      long dummy;
   };

   struct jpeg_downsampler
   {
      long dummy;
   };

   struct jpeg_forward_dct
   {
      long dummy;
   };

   struct jpeg_entropy_encoder
   {
      long dummy;
   };

   struct jpeg_decomp_master
   {
      long dummy;
   };

   struct jpeg_d_main_controller
   {
      long dummy;
   };

   struct jpeg_d_coef_controller
   {
      long dummy;
   };

   struct jpeg_d_post_controller
   {
      long dummy;
   };

   struct jpeg_input_controller
   {
      long dummy;
   };

   struct jpeg_marker_reader
   {
      long dummy;
   };

   struct jpeg_entropy_decoder
   {
      long dummy;
   };

   struct jpeg_inverse_dct
   {
      long dummy;
   };

   struct jpeg_upsampler
   {
      long dummy;
   };

   struct jpeg_color_deconverter
   {
      long dummy;
   };

   struct jpeg_color_quantizer
   {
      long dummy;
   };
#endif /* JPEG_INTERNALS */
#endif /* INCOMPLETE_TYPES_BROKEN */


   /*
    * The JPEG library modules define JPEG_INTERNALS before including this file.
    * The internal structure declarations are read only when that is true.
    * Applications using the library should not include jpegint.h, but may wish
    * to include jerror.h.
    */

#ifdef JPEG_INTERNALS
#include "jpegint.h"		/* fetch private declarations */
#include "jerror.h"		/* fetch error codes too */
#endif

#ifdef __cplusplus
#ifndef DONT_USE_EXTERN_C
}
#endif
#endif

#endif /* JPEGLIB_H */
